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Matrix Multiplication in Assembly

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In this article at OpenGenus, we have explained how to implement Matrix Multiplication in Assembly. We have provided the complete assembly code to multiply 2 3x3 matrices as well.

Table of contents:

  1. Explanation: Matrix Multiplication in Assembly
  2. Code for Matrix Multiplication in Assembly

Explanation: Matrix Multiplication in Assembly

The main components of Matrix Multiplication in Assembly are:

  • m, n and p are constants set to 3 representing the size of the input matrices (3x3 and 3x3)
  • The multiplication is performed by MUL op which multiplies AL register with an operand and stores the result in AX register.
  • The ADD op is used to add the results of the dot product of a row and column and save it in the output matrix.
  • INT op is used to write the output matrix to the standard output and exit the program.

Code: Matrix Multiplication in Assembly

Following is the complete assembly code to perform Matrix Multiplication (with descriptive comment for each line of code):

; Declare variables and constants
section .data
    ; Input matrices
    matrix1: times 3 db 1, 2, 3, 4, 5, 6, 7, 8, 9
    matrix2: times 3 db 1, 0, 0, 0, 1, 0, 0, 0, 1
    ; Output matrix
    result: times 9 db 0
    ; Constants
    m equ 3      ; Number of rows in matrices
    n equ 3      ; Number of columns in matrices
    p equ 3      ; Number of columns in matrix2

section .text
    global _start
    ; Load address of matrices into registers
    mov esi, matrix1 ; Load address of matrix1 into esi
    mov edi, matrix2 ; Load address of matrix2 into edi
    mov ebx, result  ; Load address of result matrix into ebx

    ; Initialize loop counters
    mov ecx, m      ; Outer loop counter
    mov edx, n      ; Middle loop counter
    xor ebp, ebp    ; Inner loop counter

    ; Perform matrix multiplication
    ; Initialize sum to zero
    xor eax, eax
    ; Load elements of matrices
    mov al, [esi + ebp]     ; Load element from matrix1 into al
    mov dl, [edi + ebp * p] ; Load element from matrix2 into dl

    ; Multiply and accumulate sum
    mul dl                  ; Multiply al and dl
    add [ebx + ebp], al     ; Add result to corresponding element in result matrix

    ; Increment inner loop counter
    inc ebp

    ; Check if inner loop counter has reached its limit
    cmp ebp, edx
    jl middle_loop          ; Jump to middle_loop if ebp < edx
    ; Increment outer loop counters
    add esi, n              ; Move to next row in matrix1
    add ebx, p              ; Move to next row in result matrix

    ; Check if outer loop counter has reached its limit
    dec ecx
    jg outer_loop           ; Jump to outer_loop if ecx > 0
    ; Print result matrix
    mov eax, 4              ; System call for write
    mov ebx, 1              ; File descriptor for standard output
    mov ecx, result         ; Address of result matrix
    mov edx, m * p          ; Number of bytes to write
    int 0x80                ; Call kernel to write to standard output

    ; Exit program
    mov eax, 1              ; System call for exit
    xor ebx, ebx            ; Exit status
    int 0x80                ; Call kernel to exit program

With this article at OpenGenus, you must have the complete idea of how to do Matrix Multiplication in Assembly.

Devansh Biswal

3rd year B. Tech student at Veer Surendra Sai University of Technology, Burla. Working hard day and night to get placed at Google.

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